Bioactive Substances from Marine Sources

Abstract

ABSTRACT The sea is a source of novel organic molecules of importance as bioactive agents in medicine, physiology, pharmacology and biochemistry. Groups of plants and animals which occur primarily or exclusively in marine waters probably contain new and unusual compounds and these groups have received little chemical study. Selected marine hormones, antibiotics, toxins, insecticides and novel organic molecules are reviewed. INTRODUCTION This limited review treats of some bioactive substances from marine sources; it is not comprehensive. Many drugs now in use occur naturally or are modeled after natural substances. Gosselin (1) found that almost half of all new prescriptions contained a drug of natural origin. Most of these drugs were discovered in terrestiral organisms (2) and many more are synthetics based on natural terrestrial molecules, such as the following examples in Der Marderosian's comprehensive review of marine pharmaceuticals (3): vasoconstricting drugs based on ephedrine, local anesthetics based on cocaine, and analgesics based on opium derivatives. Because four-fifths of Earth's animal life lives in or on the water (4) as does a significant portion of the planet's plant life, and because the organic chemistry of few marine organisms has been studied, an unexploited natural resource of organic molecules may await development. There are several phyla and major groups of organisms which occur only or primarily in the marine environment. For example--red and brown algae, zooxanthellae, sponges, echinoderms, molluscs, tunicates, anthozoans, and brachiopods. Included in these groups are kelp, starfish, clams, brittle stars, sea cucumbers, sea squirts, sea whips, and corals. The chemical composition of these groups certainly differ from those of terrestrial organisms, yet less than 1% of marine animals have been examined for biological activity and of these, thousands are known or thought to contain toxic compounds (5). Schwimmer and Schwimmer (6) give hundreds of references to toxic properties of marine and fresh water algae. Toxins, venoms, and poisons are substances which can cause deleterious physiological changes in man and other animals, but when administered in proper dosage, may act as beneficial drugs. Poisonous and venomous marine organisms, therefore, offer logical starting points for finding marine pharmaceuticals and yet less than six have been evaluated to the point of determining their chemical and pharmacological properties (5). Most species of poisonous fishes and a large proportion of other poisonous animals are found in the coral-reef belt. This is perhaps the major reason why Hoffman La-Roche, a Swiss-based drug firm, is establishing a laboratory in Australia for the biochemical study of organisms of the Great Barrier Reef. The belief that exclusively icthyophagus peoples were free of disease but short lived is reported in F. Adam's translation (7) of The Seven Books of Paulus Aegineta and may indicate the unknowing use of marine drugs in antiquity.